summary Focal Fibrocartilaginous Dysplasia is a rare benign bone dysplasia that leads to unilateral varus of the tibia, most commonly seen in infants. Diagnosis is made with radiographs showing an abrupt varus deformity at the metaphyseal–diaphyseal junction of the tibia with cortical sclerosis at the medial cortex. Treatment is usually observation as the majority of lesions spontaneously correct with normal proximal tibial physeal growth. Rarely, surgical deformity correction is indicated in the presence of deformity progression. Epidemiology Demographics usually seen in infant or toddlers Anatomic location most common location is tibia may also occur in humerus, forearm, phalanx, and femur Etiology Pathophysiology etiology and the pathogenesis of the deformity are unknown Associated conditions infantile tibia vara important to recognize this variation of infantile tibia vara as it can resolve without surgery Presentation Physical exam unilateral tibia vara knee hyperextension with lateral thrust can be seen Imaging Radiographs abrupt varus at the metaphyseal–diaphyseal junction of the tibia cortical sclerosis at the medial cortex radiolucency may appear just proximal to area of cortical sclerosis corresponding to the fibrocartilaginous tissue Studies Histology prominent layers of collagenic fibrous tissue with thick dense fibrocartilaginous tissue Treatment Nonoperative observation indications majority spontaneously correct because of the normal proximal tibial physeal growth Operative deformity correction indications may be necessary if the deformity progresses or fails to resolve during a period of observation or orthotic management